Carl Icahn's former protégé and a Goldman Sachs veteran have joined forces to force change at an energy infrastructure company.

Corvex Management, headed by former Icahn partner Keith Meister, and Soroban Capital Partners, founded by former Goldman trader Eric Mandelblatt, have taken a combined 9% stake in Williams Cos. The hedge funds have demanded that Williams immediately add both Meister and Mandelblatt to its board of directors.

Corvex and Soroban criticized Williams, saying mistakes had weighed on the company's value. The hedge funds did say they had held productive talks with the company.